The retrieval of hydrocarbon based fluids is pursued in subsea environments. Production and transfer of fluids from subsea wells relies on subsea installations, subsea flow lines and other equipment. Additionally, preparation and servicing of the subsea well relies on the ability to conduct subsea intervention work. A big challenge in subsea intervention work is controlling pressure so that pressurized borehole fluids in the subsea well are contained within the borehole during intervention operations.
In many applications, a pressure tight, dynamic seal is provided in the vicinity of the seabed. This type of seal allows a conveyance member, such as a wireline, slickline, coiled tubing, or other suitable conveyance, to be moved up and down inside a subsea installation, e.g. a well or flow line. The conveyance moves a tool string used in performing intervention operations. During conveyance movement, the dynamic seal contains pressurized fluids within the subsea installation to prevent escape of pressurized fluids into the environment or into a tubular, e.g. rigid riser, flexible riser, or spoolable compliant guide, connected to the subsea installation.
Some of these applications use a retrievable dynamic seal to facilitate maintenance of the dynamic seal and replacement of its sealing element. The dynamic seal can be deployed from a surface vessel to the subsea installation together with an intervention tool string and conveyance member. Similarly, the dynamic seal can be retrieved with the conveyance member for maintenance and servicing. However, difficulties can arise in positioning the dynamic seal in the subsea installation, locking the dynamic seal in place, and activating the dynamic seal.